480 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



comparatively small numbers in that month of 1913. In 



1911, it appeared in small numbers at the latter end of 

 September ; was more abundant at the same time in 1912 ; 

 and at the corresponding period of 1913 was more abund- 

 ant than in the earlier years. Graham Kerr (6) records 

 its occurrence " in immense swarms" in the waters of 

 Loch Sween in September. 



Fig. 37, PL VI, represents an ophiopluteus which 

 Mortensen (12) doubtfully correlates with Ophiopholis 

 aculeata, an Ophiuroid which, owing to its habit of con- 

 cealing itself in the cavities of stones, especially those 

 bored by Saxicava, is probably much more abundant in 

 the neighbourhood of Port Erin than is generally sup- 

 posed. A rather large and conspicuous form, this larva 

 came under my notice for the first time in February, 



1912, when a few examples of the younger stages 

 appeared in the plankton for a short time only. It again 

 appeared in February, 1913, and occurred in fair num- 

 bers in most of the plankton gatherings until the end of 

 March, when it disappeared without affording* me oppor- 

 tunities of observing the metamorphosis. 



I have now to describe briefly an ophiopluteus 

 which was first detected in the plankton of Port 

 Erin by Gravely, and named by him the " epauletted " 

 pluteus (fig. 38, PL VI). This provisional name 

 refers to the four epaulettes formed by the ciliated 

 band at the base of the postero-lateral arms, a feature 

 so conspicuous as to make the larva easily recog- 

 nisable. The ends of all the arms are somewhat club- 

 shaped. Noticed for the first time in July, 1907, and 

 again recorded in the same month in 1908, its occurrence 

 in our local plankton was comparatively rare; and I 

 have not observed it since 1909. Graham Kerr (6), on 

 the other hand, records its occurrence in " immense 



